Radiant lining

ABSTRACT

The radiant screen lining comprises a plurality of randomly oriented discrete strands of heat resistant metal pressed into a mat of appropriate density and thickness. The mat is applied to a variety of heating apparatus by suitable securing means and positioned therein to interfere with radiated heat so that each strand is heated and radiates its heat for utilization by the heating apparatus. The lining can be applied to the inner walls of an oven, furnace, fire box, and the like.

Utd States Patent 91 Ulbrich 51 Feb. 27, 1973 1 RADIANT LINING [76] Inventor: Richard W. Ulbrich, 126 West Dixon Ave., Dayton, Ohio 45419 [22] Filed: Feb. 1, 1971 [21] Appl. No.: 111,355

[52] US. Cl. ..263/40 R, 431/347 [51] Int. Cl ..F27b 3/02 [58] Field of Search ..263/40 R, 43, 50; 431/347 [56] References Cited UNITED STATES PATENTS 11/1966 Ulbrich ..263/40 R 12/1966 Partiot ..43 11347 X Primary ExaminerJohn J. Camby AttorneyPhillip L. DeArment [57] ABSTRACT The radiant screen lining comprises a plurality of randomly oriented discrete strands of heat resistant metal pressed into a mat of appropriate density and thickness. The mat is applied to a variety of heating apparatus by suitable securing means and positioned therein to interfere with radiated heat so that each strand is heated and radiates its heat for utilization by the heating apparatus. The lining can be applied to the inner walls of an oven, furnace, fire box, and the like.

19 Claims, 7 Drawing Figures PATENTED 3.718.323 .SHEET 1 or 2 INVENTORI RICHARD w ULBRICH BY 6 x. 4m

AT TORI-1F PATENTEB FEBZ 7 I975 SHEET 2 0F 2 FIG. 7

FIG. 6

INVENTOR RICHARD w. ULBRICH BY 91090 61m ATTORNEY RADIANT LINING BACKGROUND OF THE INVENTION This invention relates to a lining for furnaces, ovens, kilns, boilers, vats, and various types of heating apparatus.

The heating industry in general is not as accustomed to using radiant heating as it is to the much more prevalent methods of heating by convection and conduction. There are several methods to generate radiant heat, or the infra-red waves constituting radiant heat. The common method for generating radiant heat is to use infra-red electric lights, or infra-red gas burners, surrounded by reflectors, such as polished aluminum. These methods are limited by the maximum temperature the reflector can withstand, which for aluminum is in the neighborhood of 800F.

Another method for generating radiant heat is to surround an infra-red burner in a chamber with a number of layers of wire mesh screen to increase the radiation surface area. In this application, the walls, door, roof, and bottom of a chamber surrounding the radiant burner would be lined with multiple layers of radiant woven-wire mesh screening. This method appears to be the most efficient of the current state-of-the-art methods of obtaining rapid radiant heat-up and cooldown for temperatures up to about 2,lF and is represented by applicants U.S. Pat. No. 3,282,578.

The mesh screen lining, however, presents a problem in arranging the numerous screens to close the open areas of screen by adjacent screens. This is necessary to prevent the radiant rays from radiating beyond the layer farthest from the heat source. The aboveidentified patent proposes use of different gauge wire and mesh numbers for the screens comprising the screen lining to present as much surface radiating area for a given lining volume as possible and in this way minimize the quantity of radiation passing through open areas in the lining. This solution leads to complex construction problems involving installing and anchoring numerous unwieldy screen layers of different wire meshes and wire gauges to inside surfaces of a chamber. Yet open areas may still occur in spite of precise calculations and manufacturing techniques.

The present invention includes as a preferred embodiment a radiant lining comprising a plurality of randomly oriented metal strands or wires compressed into a mat or pad configuration. The mats are installed against the inner wall of the'furnace, or other heat chamber so as to be directly exposed to the heat. This lining is intended to be used in lieu of the present lining of firebrick, insulating brick, fire clay, or multiple layers of radiant woven-wire mesh screening. However, the lining can be applied over conventional insulating materials in existing devices to upgrade performance.

The material selected for the wire wool-mesh mat must be able to withstand the maximum operating temperature and environment of the heating apparatus in which it is to be used. The material may be stainless steel or high temperature nickel-steel alloys for temperatures up to 2,l00F. For temperatures above 2, 1 00F, a radiating thermal attenuator may be applied between the lining and the heat source. An example of a commercially available attenuator suitable for this application is ceramic honeycomb.

A typical, inexpensive, and readily-available source of lining material is stainless steel or nickel-steel tumings from finishing cuts on a machine tool. For higher temperature applications, material of ceramic or carbon strands, or other such high temperature materials may be used.

The radiant lining according to the present invention provides an effective radiating surface area which is many times larger than a comparatively flat surface of firebrick or other solid insulating material. As heat from the burners in a fossil-fuel furnace, or electrodes in an electric furnace, raise the temperature of the radiant lining, its larger radiating surface radiates and reradiates back and forth inside the furnace, or other similar heat chamber, with an accumulative effect. Since heat radiation has a fourth power relationship to temperature, the result is an extremely rapid rise in temperature for even a modest input of fuel or electric power.

The strands of wire radiate in straight lines in all directions. Some of the rays of radiant energy are radiated back into the heat chamber to impinge on, and give off, the radiant energy in the form of heat to the charge and to strands of wire on opposite walls. Some radiant rays will be given off to adjacent strands of wire, and other rays will be radiated away from the furnace chamber into adjacent wire strands, which in turn radiate. Thus, the amount of re-radiated heat received and re-radiated by each succeeding wire strands is gradually attenuated down to the last wire. The'primary limitation on the use of radiant lining is the maximum operating temperature of the furnace, which must not exceed the melting or oxidizing point of the lining material.

It is, therefore, an object of this invention to provide an improved lining for a furnace, oven, kiln, boiler, or other such heat chamber and which generates radiant infrared heat more efficiently than those of prior art.

An additional object of this invention is to simplify the manufacture, installation, and removal of an efficient radiant lining for furnaces, etc.

Another object of this invention is to provide a radiant lining which uses lower cost materials by utilizing stainless steel or similar high temperature alloy tumings.

These and other objects will become apparent to one skilled in the art from the following description of the invention made in conjunction with the drawings and in which:

FIG. 1 is a perspective view of a radiant lining mat embodying the present invention;

FIG. 2 is an elevational view of a portion of the mat of FIG. 1 on a larger scale;

FIG. 3 is a sectional view of an oven incorporating the radiant lining according to the present invention;

FIG. 4 is a perspective view with parts broken away of another type of heating apparatus which incorporates an application of the radiant lining according to the present invention;

FIG. 5 is a perspective view similar to FIG. 4 of another type of heating apparatus to which the radiant lining has been applied;

FIG. 6 is a sectional view of still another type of heating apparatus embodying the radiant lining of the present invention;

FIG. 7 is a partial sectional view of a wall of a heating apparatus illustrating a thermal barrier according to the present invention.

Referring to the drawings which illustrate preferred embodiments of the invention and initially to FIG. 1, which discloses a radiant lining panel 10 according to the present invention. Panel 10 is illustrated as being rectangular and including an edging or frame 12 enclosing a mat 14. The frame 12 is preferred where the configuration of the heating chamber permits such as in a regular-shaped heating chamber. It should be appreciated, however, that there may be application for the lining where the use of a frame such as frame 12 is not practical. However, where practical, it is preferred since it makes the mat 14 easier to handle, install, and

remove.

The mats 14 comprise a plurality of randomly oriented wires or strands 16 of heat resistant material pressed into a mat-like configuration. The discrete strands 16 should be made from material that is capable of withstanding the heat and corrosive effects of the heating environment in which it is to be used. For example, it has been found that many of the stainless steels or high temperature nickel-steel alloys are suitable for temperatures below 2,100F. One relatively inexpensive source for strands 16 is finishing turnings produced by machine tools. When turnings are used for strands 16, they are normally received in a random orientation relative to one another and they can be loaded into a suitable pressing apparatus of the appropriate configuration and dimension. After pressing the strands 16, a fairly stable mat 14 is provided.

The random orientation of the strands is illustrated in FIG. 2. Each strand presents substantially its entire surface area as a radiating surface, and when compressed into the mat, it provides a substantial increase in radiating surface area as compared to a screen or a continuous surface. I

The density and thickness of the mat varies depending on the operating temperature, gauge of the wire, type of wire used, size of chamber, and space available. There is a point of diminishing returns for the amount of re-radiation obtained by increasing the mat density per unit volume of radiant lining. This point is where the mat density approaches that of a solid radiating panel. Therefore, a density should be selected which presents the optimum surface area without defeating its ability to radiate.

FIGS. 3 through 7 illustrate examples of typical heating apparatus and how the lining may be applied to each of these representative types of devices. It should be apparent that numerous other types of heating devices may also utilize the radiant lining according to the present invention.

FIG. 3 discloses a generally rectangular shaped furnace or heating apparatus 20. The furnace 20 comprises an outer shell 22, a layer of insulation 24, and radiant lining panels 10. The panels 10 can be removably inserted into the heating chamber through channels 26 and secured in place by suitable locking means. For irregular configurations, the mats 14 with or without frame 12 can be secured directly to the insulation 24 by means of suitable fastening devices.

When the mats 16 are installed as shown in FIG. 3 and heat is directed to the charge C from the fossil-fuel burners 27, heat is radiated toward the radiant lining 14. The radiant energy heats the strands l6, and each strand 16 in turn radiates heat. Part of the radiation is directed toward charge C while other portions are intercepted by other strands 16 of the lining 14. The net result of operation of the lining is to conserve the energy radiation from the heating chamber 25 and redirect it back into the chamber 25 to produce economies heretofore unrealized. In addition to conserving fuel to produce a given heat, the lining also reduces the time required to reach a particular heat and the time required to cool down after a given heat has been reached.

The embodiment of the invention shown in FIG. 3 incorporates fossil-fuel burners. However, electrical heating elements, electric arcs, or other heat sources may be used as the heat source with the same advantages.

The lining 14 may be applied as illustrated in FIG. 3 or it can be applied over existing insulation such as firebrick. Also, in existing ovens, a benefit can be obtained by merely covering the mouth or inlet to the exhaust for the oven, such as exhaust 28 in FIG. 3, with an appropriately configured mat 14. In this application, the mat 14 is heated by hot gas passing therethrough in the process of exhausting as well as by radiation from chamber 25. The mat 14 in turn radiates the heat back into chamber 25, leaving only the exhaust flue gases to pass out the flue at approximately one-half the operating furnace temperature.

The heating apparatus 40 disclosed in FIG. 4 is intended to be representative of heating devices heated by fire tubes. Examples of these devices are boilers and vat cookers commonly employed in the food industry. The apparatus 40 comprises a vat structure 42 which receives the substance to be heated. Heat is transferred to the vat 42 through a series of heat pipes or fire tubes 44 located beneath the vat. Heat is directed into the tubes 44 by a plurality of gas nozzles 46 which are positioned to direct flame into the forward end of tubes 44. The tubes 44 are heated by the flame and transfers heat to the vat 42. The gas is exhausted from tubes 44 into flues 48.

In the embodiment shown in FIG. 4, a radiant insulation mat 14 is inserted into the fire tubes 44 at a location such that the hot gases pass through the mat before entering flues 48. The mat 14 is thereby heated and radiates heat back into the fire tubes 44, thereby reducing the flue gas temperature for greater utilization of heat, and also distributing the heat more evenly throughout the surface of the fire tubes.

The heating apparatus 41 disclosed in FIG. 5 illustrates another type of vat cooker. As illustrated in this figure, a rectangular fire box 49 transfers heat from gas nozzles 46 into liquid in contact with plate 50. The fire box 49 has mats 14 applied to all sides thereof except plate 50. The fire box 49 is exhausted by flue 51 through openings 52.

The heating apparatus disclosed in FIG. 6 is representative of another type of heating apparatus 54 which anneals pipe welds. The pipe annealing apparatus 54 includes an outer circular shell 55 comprised of two hinged parts which can be wrapped about the welded area of a pipe and locked. A plurality of heating devices 56 are spaced about the periphery of shell 52. A suitable insulating material 58 is applied to the interior of shell 52 between heating units 54. The

radiant lining 14 is suitably applied to the insulation 54 i and exposed to the pipe P. For this application, the mat 14 is of tubular configuration and operates to radiate heat to pipe P and primarily to the weld between adjacent sections of pipe. The heat radiated from the pipe exterior is intercepted by the lining to minimize heat losses.

The foregoing applications of the lining are illustrative of several typical applications of the pressed mat lining 14 and it should be apparent to those skilled in the art that many other applications for the pressed mat exist but have not been disclosed specifically.

The application of the lining disclosed heretofore used metal strands 16 which may be metal turnings, and such lining material has been satisfactorily tested for applications up to 2,100F. For example, a furnace similar to the furnace disclosed in FIG. 3 was built and tested. The heating chamber 25 was 25 X 8 X inches, the insulation 24 was 5 inches thick, mat 14 was 2 inches thick, and burners 27 were commercially available gas burners modified to prevent pre-ignition in the mixing chamber. This furnace was brought up to 2,100F. in 6 minutes. The panels 10 were removed after the tests were completed and showed no deterioration from the temperatures reached in the test.

However, for environments in excess of 2,100F, it is necessary to use a radiant thermal attenuator with the mat or lining 14. FIG. 7 discloses a wall section 60 for a heating chamber. The wall section 60 includes a shell 62, insulation 64, mat 14, and thermal attenuator 66. The wall orientation is such that thermal attenuator 66 is directly exposed to the heat. The thermal attenuator illustrated represents one type of ceramic honeycomb material suitable for this application which is a slant cell honeycomb manufactured and sold by DuPont under the trademark TORVEX. When the TORVEX honeycomb is applied to the face of the lining 14, it reduces the temperature to which the lining l4 and insulation 64 is exposed. The lining 14 is heated by heat passing through the inclined openings 68. When the lining 14 is heated, it radiates heat back into the chamber 25 through openings 68; This configuration substantially increases the operating temperature for which the lining according to the present invention has application.

What is claimed is:

1. An apparatus for generating heat in a heating chamber for an oven adapted to receive a charge to be heated comprising, means for directing heat toward said chamber, and radiant lining means contiguous to at least a portion of said chamber for intercepting heat leaving the chamber and radiating heat back into the chamber, said radiant lining means comprising a plurality of discrete strands formed into a mat, said mat being configured to approximate the contiguous portion of said chamber.

2. An apparatus as defined in claim 1, wherein said discrete strands comprise metal turnings.

3. An apparatus as defined in claim 2, wherein said metal tumings are stainless steel.

4. An apparatus as defined in claim 2, wherein said discrete strands are an alloy of nickel-steel.

5. An apparatus as defined in claim 1, wherein said means for directing heat includes means for generating heats in said chamber in excess of 2,100F and further including means disposed intermediate said chamber and said mat for providing a thermal attenuator for said mat.

6. An apparatus as defined in claim 5, wherein said means for providing a thermal barrier comprises a ceramic honeycomb having openings therein inclined relative to said chamber.

7. An apparatus as defined in claim 1, wherein said radiant lining means further includes a frame forming an edging disposed about the peripheral edges of said mat.

8. A radiant lining adapted to be disposed about at least a portion of a heated area and exposed to said area to receive heat therefrom, said lining comprises a plurality of randomly oriented discrete strands of heat resistant material pressed into a stable mat structure whereby the surface of each strand becomes a radiating surface when heated, and a frame extending around the peripheral edge of said mat.

9. A radiant lining as defined in claim 8, wherein said strands are made from metal turnings.

10. A radiant lining as defined in claim 9, wherein said strands are stainless steel.

11. A radiant lining as defined in claim 9, wherein said strands are an alloy of nickel-steel.

12. An apparatus for generating heat in a plurality of tubes adapted to exchange heat directed therein to a medium in contact with the exterior thereof and including means for exhausting said tubes, and radiant lining means disposed within said tubes and radiating heat back into said tubes, said radiant lining means comprising a plurality of discrete strands formed into a mat configured to approximate the contiguous portion of said tubes, said mat being disposed immediately upstream of said means for exhausting said tubes.

13. An apparatus as defined in claim 12, wherein said discrete strands comprise metal turnings.

14. An apparatus as defined in claim 13, wherein said metal tumings are stainless steel.

15. An apparatus as defined in claim 13, wherein said discute strands are an alloy of nickel-steel.

16. An apparatus for generating heat in a confined area including the circumference of a weld joining two pipe sections comprising means for directing heat toward said area, and radiant lining means contiguous to at least a portion of said area for intercepting heat leaving said area and radiating heat back into said area, said radiant lining means comprising a plurality of discrete strands formed into a mat configured to approximate the contiguous portion of said area.

17. An apparatus as defined in claim 16, wherein said discrete strands comprise metal turnings.

18. An apparatus as defined in claim 17, wherein said metal turnings are stainless steel.

19. An apparatus as defined in claim 17, wherein said discrete strands are an alloy of nickel-steel. 

2. An apparatus as defined in claim 1, wherein said discrete strands comprise metal turnings.
 3. An apparatus as defined in claim 2, wherein said metal turnings are stainless steel.
 4. An apparatus as defined in claim 2, wherein said discrete strands are an alloy of nickel-steel.
 5. An apparatus as defined in claim 1, wherein said means for directing heat includes means for generating heats in said chamber in excess of 2,100*F and further including means disposed intermediate said chamber and said mat for providing a thermal attenuator for said mat.
 6. An apparatus as defined in claim 5, wherein said means for providing a thermal barrier comprises a ceramic honeycomb having openings therein inclined relative to said chamber.
 7. An apparatus as defined in claim 1, wherein said radiant lining means further includes a frame forming an edging disposed about the peripheral edges of said mat.
 8. A radiant lining adapted to be disposed about at least a portion of a heated area and exposed to said area to receive heat therefrom, said lining comprises a plurality of randomly oriented discrete strands of heat resistant material pressed into a stable mat structure whereby the surface of each strand becomes a radiating surface when heated, and a frame extending around the peripheral edge of said mat.
 9. A radiant lining as defined in claim 8, wherein said strands are made from metal turnings.
 10. A radiant lining as defined in claim 9, wherein said strands are stainless steel.
 11. A radiant lining as defined in claim 9, wherein said strands are an alloy of nickel-steel.
 12. An apparatus for generating heat in a plurality of tubes adapted to exchange heat directed therein to a medium in contact with the exterior thereof and including means for exhausting said tubes, and radiant lining means disposed within said tubes and radiating heat back into said tubes, said radiant lining means comprising a plurality of discrete strands formed into a mat configured to approximate the contiguous portion of said tubes, said mat being disposed immediately upstream of said means for exhausting said tubes.
 13. An apparatus as defined in claim 12, wherein said discrete strands comprise metal turnings.
 14. An apparatus as defined in claim 13, wherein said metal turnings are stainless steel.
 15. An apparatus as defined in claim 13, wherein said discute strands are an alloy of nickel-steel.
 16. An apparatus for generating heat in a confined area including the circumference of a weld joining two pipe sections comprising means for directing heat toward said area, and radiant lining means contiguous to at least a portion of said area for intercepting heat leaving said area and radiating heat back into said area, said radiant lining means comprising a plurality of discrete strands formed into a mat configured to approximate the contiguous portion of said area.
 17. An apparatus as defined in claim 16, wherein said discrete strands comprise metal turnings.
 18. An apparatus as defined in claim 17, wherein said metal turnings are stainless steel.
 19. An apparatus as defined in claim 17, wherein said discrete strands are an alloy of nickel-steel. 